Valve rhombic-elliptical, obtuse at the ends; axial area narrow, central rounded, small; striæ punctate, slightly radiate, about 19 in 10 µ; terminal fissures close to the ends, indistinct. L. 60 µ. Cleve describes this form as having acute ends, while Gregory states that it is "more obtuse and broader than N. rhombica." Gregory's Figure 101 apparently shows the ends acute, but he says that the valve view is "rhombic or elliptic-lanceolate, broad, with obtuse ends" (Diat. of the Clyde, p. 57, Pl. 6). Hackensack Swamp, N. J. Pl. 31, Fig. 5. ORTHOSTICHÆ CL. Valve lanceolate or elongated; axial area narrow; central area sometimes apparently dilated into a stauros; striæ punctate, the puncta in transverse and longitudinal rows. {100}NAVICULA CUSPIDATA KUETZ. Valve rhombic-lanceolate, with acute ends; axial area linear, narrow, not widened in the middle; striæ transverse, 14-19 in 10 µ (Cl.). L. 70-150 µ. Blue clay. Not uncommon in fresh water. Pl. 26, Figs. 1 and 2. Fig. 2 represents an inner valve or stratum, with strong costæ variable in size, formerly known as Surirella craticula Ehr. _N. cuspidata var. ambigua (Ehr.) Cl._--Valve elliptical-lanceolate, with rostrate ends, smaller than the type and with finer striæ. Crum Creek. Pl. 26, Fig. 3. NAVICULA SPICULA (HICKIE) CL. Valve narrow, lanceolate with acute ends; axial area narrow, central area dilated into a stauros reaching the margin; transverse striæ, 25-29 in 10 µ, longitudinal closer. L. 50-130 (Cl.). Sometimes confused with N. crucigera. _Stauroneis spicula_ Hickie. Newark, N. J. Pl. 26, Fig. 4. NAVICULA CRUCIGERA (WM. SM.) CL. Valve lanceolate, narrow, with acute apices; central nodule a stauros reaching the margin but crossed by two or three coarser striæ; transverse striæ, 12 in 10 µ, punctate, the puncta about 25 in 10 µ. L. 80-100 µ (Cl.). Frustules in gelatinous tubes or free. _Schizonema cruciger_ Wm. Sm. Pl. 26, Fig. 15. Reported as occurring in New York Bay, but I have not seen it. The figure is from a specimen from another locality. MINUSCULÆ CL. Valve lanceolate or elliptical, chiefly distinguished by the small size; axial area indistinct; central area small; striæ radiate, very finely punctate. NAVICULA ATOMUS NÆGELI Valve elliptical, 6-8 µ in length; striæ radiate, 26-30 µ, closer near the ends; axial area linear, scarcely widened in the middle. Water-troughs and ditches. Probably common, but frequently not noticed because of its minuteness. A mounting medium of the highest refractive index, such as realgar, is required to resolve the striæ. In the figure the striæ are drawn a little coarser than they appear in most specimens. Pl. 26, Fig. 12. LÆVISTRIATÆ CL. Valve lanceolate, axial area distinct; central area orbicular; striæ coarse, indistinctly punctate, approaching the costæ of Pinnularia. {101}NAVICULA YARRENSIS GRUN.